Substituted lophine compounds



United States Patent 2 Claims. (Cl. 260-309) This is a division of Ser.No. 127,803, filed July 31, 1961, now US. Patent 3,205,083 of Sept. 7,1965.

This invention relates to methods of imparting resistance todeterioration from sunlight by the inclusion of minor amounts ofcompounds related to 2,4,5-triphenyl imidazole in compositionscontaining a major portion of synthetic macromolecular materials such assynthetic plastics, resins, or elastomers. The invention also concernscertain novel compounds. The useful life of synthetic fibers, films,elastomerics and similar polymerictype materials can be increased byimprovement of the physical and/ or esthetic properties. The greaterlongevity of such macromolecular materials is of considerable importancein practical considerations. Inasmuch as an appreciable proportion ofdeterioration can result from exposure to light, techniques forminimizing the detrimental effect of the more potent light-forms arehighly desirable. The light-forms in and around the ultra-violet rangehave considerable potency in exhibiting adverse effects on themacromolecular structure of many varieties of polymerictype materials.Recently, some manufacturers have marketed formulations comprising suchmaterials in combination with small amounts of agents effective inminimizing the damaging nature of sunlight and other light-forms strongin the ultra-violet region and such formulations have been recognized asa marked advance. This advance has merit with macromolecular materialssuch as polyacrylates, polyolefins, polystyrenes, cellulosics,polyesters, polyvinyls and the like.

Heretofore, 2,4,5-triphenyl imidazole as well as certain derivativesthereof have been described, as in Hofmanns text (1950) on Imidazoles,but there has not been any recommendation for the use of such compoundsas ultra-violet absorbers in formulations with macromolecular materials.Derivatives of 4,5-diphenyl imidazole may be prepared by reacting anaromatic aldehyde with ammonia and benzil in the presence of ammoniumacetate in acetic acid to form 2-(aryl)-4,5-diphenyl imidazole inaccordance with the following equation in which A refers to the aromaticgroup:

CrH,-,C=O

(Acetic Acid) 2NH A0110 GnH5-C=O i C6H5-C-N CBH5-C-N In accordance withthe present invention, synthetic macromolecular materials are made moreresistant to deterioration when subjected for prolonged periods tosunlight by reason of the ultra-violet absorptivity or a minorconcentration of certain derivatives of 2,4,5-triphenyl imidazole.Preferred compositions consist 'of a polymeric material and a minoramount of a compound such as:

Patented Jan. 2, 1968 (a) 1,4-bis-(4,5-diphenyl-2-imidazolyl)-benzeneing the formula:

H H Q ll L Q Q H (b) 2-(4-dimethylaminophenyl) 4,5 diphenyl imidazolehaving the formula:

(c) 2 (1 naphthyl) 4,5 diphenyl imidazole, having the formula:

hav-

(d) 2 (2 hydroxy 5 tertiarybutyl phenyl) 4,5- diphenyl imidazole, havingthe formula:

and/ or (e) 2-(2 methoxy phenyl)-4,5-diphenyl imidazole, having theformula:

| H300 O-N I ll Q The present invention includes such novel compounds.The present invention also includes compositions consisting of apolymeric material and a minor amount of at least one derivative of2,4,5-triphenyl imidazole having the formula of:

in which A is an aryl group; Q is a substituent selected from the groupconsisting of hydroxyl, alkoxyl, aroxyl, ortho-substituted C H moiety ofnaphthyl, amino-, monoand dialkylamino-, and 4,5-diphenyl imidazolyl; Ris tertiary butyl; x is a number from 1 to 2; y is 0 to 2. Examples ofother compounds which absorb ultra-violet light and are within the scopeof said formula include the derivatives of 2,4,5-triphenyl imidazole inwhich the 2- phenyl group has substituents such as: 2-hydroxy; 3-hydroxy; 4-hydroxy; 3-methoxy; 4-methoxy; Z-dimethylamino; and3-dimethylamino.

The invention is further clarified by reference to a plurality ofexamples.

3 Examples I-V A resin kettle of appropriate dimensions can be employedin preparing irnidazole derivatives from benzil, ammonia, and anaromatic aldehyde. Data relating to the preparations include:

One set of samples is prepared by including in each sample 1.5 parts byweight of one of the arylimidazole compounds of Examples I-V as theultra-violet absorber plus 100 parts by weight of polyvinyl chloride,dioctylphthalate, 50: barium-cadmium laurate, 2: and triphenyl ExampleNo 1 2 3 4 5 Capacity of kettle, l 2 2 0. 5 2 1 Benzil, g 52. 5 52. 510. 5 105 Acetic acid, ml 1, 000 1, 000 244 1, 200 300 onium acetate, g155 150 32 30(8) 10(1) Refiuxiug hours Quenching solution:

Percent minimum transmission of ultra-violet Range of maximum percentabsorption expressed as millimicron wave length:

Lower Upper 390 In preparing 1,4-bis-(4,5-diphenyl-2-imidazolyl)-benzenein accordance with Example I, 16.7 g. (0.125 mol) of terephthaldehydewas mixed with 52.5 g. (0.25 mol) of benzil and 155 g. (2 mols) ofammonium acetate in 1 liter of acetic acid, and the mixture was heatedat reflux temperature for tWo hours. The reaction mixture was pouredinto 12 liters of water, which dissolved the acetic acid and by-productsand precipitated the product. After drying in a vacuum oven, the productwas dispersed in hot pyridine containing a small amount of water, andclarified by a small amount of charcoal, and the thus clarified solutionwas cooled to recrystallize the compound and the clarification andrecrystallization steps were repeated;

Examples IIV followed the same pattern, but employed'appropriatealdehydes as indicated.

Example Aldehyde 4,5-diphenylimidazole Derivative 1 Terephthalde-1,4-bis-(4,5-diphenyI-Z-imidazolyl)- hyde. benzene.

2 4-dimethylamino- 2-(4-dimethylaminophenyD-4,5-

benzaldehyde. diphenyl imidazole.

3 l-rlilapihthalde- 2- (l-naphthyl)4,5-diphenyl imidazole.

y e. 4 E-t-butyl salecyl- 2-(2-hydroxy-E-tertiarybutyl phenyl)- 1aldehyde. 4,5-dipheuyl imidazole.

5 Q-InethOXy-benZaL 2-(2-methoxyphenyl)-4,5-dipl1enyl dehyde. imidazole.

Example VI Samples of polymeric-type materials are prepared with theindiacted modifications by the incorporation of minor amounts of thea-ryl-imidazole compounds of each of Ex amples I-V and subjected toultra-violet aging tests including exposures to Fade-O-Meter, G.E.S-1sun lamp and/or outdoor exposure.

phosphite, 1. Similar testing of the elfectiveness of the saidultra-violet absorbers is made with low-density polyethylene containing0.1 to 1.0 weight percent of the absorbers; and in polystyrenescontaining 0.25% to 0.5% by weight of such absorbers. Similar tests aremade with polyesters prepared from polyester resin catalyzed with 2%benzoylperoxide and containing 0.25 to 0.5% by weight of theseultra-violet absorbers. A different set of samples is prepared using 78parts by weight of cellulose acetate (56% combined acetic acid, andviscosity of 50 seconds); 5 parts by weight of triphenyl phosphate; 12parts by weight of diethylphthalate; 5 parts by Weight ofdimethylphthalate; and 1 to 3 parts by weight of one or more of theaforesaid ultra-violet absorbers.

The aryl-imidazole compounds of Examples l-V have little, if any,noticeable effect on the strength, appearance and similar physicalcharacteristics of the polymeric-type products even when several timesthe effective amount is incorporated in the formulation; the efiFectiveamount being approximately equivalent to the concentrations employedindustrially for ultra-violet absorbers. The results of the aging testsdemonstrate resistance to deterioration quite superior to results onsimilar compositions lacking the ultra-violet absorbers, and superior aswell to results to control samples consisting of similar compositionscontaining effective amounts of commercially marketed ultravioletabsorbers, difiering in chemical structure from the structure of theimidazole compounds of this invention.

Samples are prepared consisting of a major amount of polystyrene and aminor amount of an absorber of ultaviolet light. The control samplescontain commercially marketed U.V. absorbers in concentrations of 0.08,0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 4.8 and 6.0%, and the samples beingevaluated contain the same series of concentrations of the triarylimidazole. The UV. absorbers within the scope of the formula (C H C N HAin which A is 3- hydroxyphenyl, 4-hydroxyphenyl, 4-methoxyphenyl, 2-hydroxyphenyl, Z-dimethylaminophenyl, 3-dimethylarninophenyl and3-methoxyphenyl are shown to be as effective as the commerciallymarketed absorbers, and a basis is established for the commercialsignificance of the range from 0.1 to 5% for the concentration of the2,4,5 triarylimidazole absorbers.

Obviously many modifications and variations of the in vention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and there- OTHER REFERENCES fore only such limitationsshould be imposed as are inc k t 1,; J Chem, Soc, (L don), 1941, pp.dicated in the appended claims.

The invmtion claimed is: Cottman et al.: Proc. Indiana Acad. Sci., vol.47, pp.

1 14-bis-(4 S-di hen limidazol 1)-ben2ene 5 124-9 (1938)' p y Neugebaueret al.: German application 1,106,599,

2. 2-(2-hydroxy-5-tert1ary butyl pheny1)-4,5-d1pheny1 (May 10, 1

imidazole. Radziszewski Chem. Abst, v01. 4, pp. 2265-6 (1910).

References Cited 10 JOHN D. RANDOLPH, Primary Examiner. FOREIGN PATENTSWALTER A. MODANCE, Examiner.

585,555 4/ 1960 Belgium. N. TROUSOF, Assistant Examiner.

1. 1,4-BIX-(,5-DIPHENYL IMIDAZOLYL)-BEZENE.
 2. 2-(2-HYDROXY-5-TETIARYBUTYL PHENYL)-4,5-DIPHENYL IMIDAZOLE.